Question

7.
The mole fraction NaOH in the aqueous solu-
tion is 0.001. The molarity of NaOH solution
will be
(1) 0.056 M
(2) 55.55 M
(3) 0.001 M
(4) Data is insufficient.
​

Answer 1

Explanation:

Molarity of NaOH solution is = (W/(M*V))

hare mole fraction of NaOH is 0.5

that is 0.5mol H2O+0.5 mol NaOH

i.e. 18*0.5g water+40*0.5g NaOH [MW of water = 18, NaOH=40]

i.e. 9.0g water+20g NaOH

i.e. 9mL water+20/4mL NaOH [Applying v=m/d]

i.e. 9mL water+5mL NaOH

i.e. TOTAL VOL OF THE SOLUTION IS 14mL=14/1000 L

using 1st equation here

now molarity of NaOH solution is = ((20*1000)/(40*14) = 35.71